1. Field of the Invention
This invention relates to a method for feeding a blocked sheet unit which can be advantageously put into practice when, for example, printed paper sheets are blocked in a predetermined unit of accumulated paper sheets and feeding such blocked sheet units to a subsequent step one after another, and more particularly to a method for blocking sheets such as paper sheets, synthetic resin sheets and metal sheets and continuously feed such sheets. The method of the present invention is most advantageously carried out especially when such sheets are comparatively long.
2. Description of the Prior Art
Japanese Patent Application Early Laid-Open Publication No. Sho 61-248856 owned by the present applicant teaches a method for feeding a blocked sheet unit, in which sheets of a predetermined length are continuously fed to a sheet unit forming section for accumulation, and a blocked sheet unit composed of a predetermined number of accumulated sheets is taken out and fed to a subsequent step. According to this method, as shown in FIG. 1, the front edges of sheets a which are successively fed are temporarily received by a manipulation claw 100, and in the meantime, a blocked sheet unit A composed of a predetermined number of sheets already accumulated below the position where the front edges of sheets a are temporarily received is taken out in its entirety by a gripper 200, and after the blocked sheet unit A is taken out, the manipulation claw 100 temporarily stops receiving the front edges of sheets a, and then the accumulation of sheets is resumed until they reach the predetermined number, and another blocked sheet unit A taken out by the gripper 200 is fed to a subsequent step by a transferring apparatus such as, for example, a pusher 300. According to this method, it is an essential condition that the entire length of the blocked sheet unit A be completely taken out from the sheet unit forming section by the gripper 200. In the case where the sheet unit is long, the stroke W.sub.1 of the gripper 200 always is a distance greater than the entire length of the sheet unit.
However, in the above-described prior art device, since it starts the subsequent step only after the entire length of a blocked sheet unit is taken out from a sheet unit forming section, each take-out stroke W.sub.1 takes a long time during the overall operation. As a result, the take-out efficiency (sheet unit feeding speed) is lowered which makes it difficult to follow the sheet accumulation steps with high speed subsequent steps. Therefore, it is the actual situation that the increase of efficiency of the line as a whole (e.g., book processing line, etc.) cannot be achieved. Particularly, in the case where the sheet unit operating time is comparative long, the prior art apparatus has the drawback in that the productivity thereof is considerably lowered.
The present invention has been accomplished in order to eliminate the above-described problems and drawbacks inherent in the prior art apparatus.